He writes that people who “threaten violence” on Twitter have been arrested:

Earlier this week, DHS agents detained Irish traveler Leigh Van Bryan and a friend at Los Angeles International Airport and sent them back to Europe after Bryan tweeted that he was going to “destroy America” and dig up Marilyn Monroe during his trip — references, he later told officials, to partying and the comedy show Family Guy, respectively (the incident conjured up memories of other jokes gone awry, such as when the Onion enraged the U.S. Capitol Police by tweeting, “BREAKING: Witnesses reporting screams and gunfire heard inside Capitol building”). In 2009, FBI agents arrested an Oklahoma City man named Daniel Knight Hayden for threatening on Twitter to kill police officers during a Tea Party tax protest. Hayden was sentenced to eight months in prison.

Annalee Newitz is an American journalist who covers the cultural impact of science and technology. She is the editor-in-chief of io9, which named in 2010 as one of the top 30 science blogs by The Times. Her work has been published in Popular Science, Wired, Salon.com, New Scientist, San Francisco Chronicle, Washington Post, and AlterNet, and she is a regular lecturer at colleges and conferences.